Well. Because I'm curious as to if it wont be enough. I added new fish. I know have my 8" albino aro, a 7-8" ngt datnoid, and now just added 2) 5" BDxHEN ray pups.If you buy one made its probably $500 ish...
If you go the diy route the others are suggesting you will save $$
Why are you going away from the fx6 or are you just adding?